In oil and gas wells, both liquids and gases may be produced from the same well. In such wells, it is often desirable to separate gases and liquids so that the liquids may be more efficiently pumped or lifted to the surface. Gases that may be entrained or evolved from hydrocarbon liquids when such liquids are pumped to the surface may interfere or reduce the efficiency of the pumping operations, decreasing or slowing production.
There have been a variety of different methods and devices used for such downhole separation of liquids and gases. One such separator device 10 is shown in FIG. 1 and includes a tube 12 that is positioned within and welded at one end by means of a plate or annular ring 14 to the interior of a larger diameter tube 16. The larger diameter tube 16 is subsequently attached (screwed) at its upper end to a tubing string that extends into the well borehole from the surface. The larger diameter or outer tube 16 may be ported or slotted at its upper end to allow liquids and gases that are introduced into the outer tube to escape into the borehole or casing. The lower end of the inner and outer tubes 12, 14 are coupled together by a sub or coupling 18, which may, in turn, couple to a packer (not shown) that anchors the tubing string within the well. The packer forms a sump area where liquids, which fall back into the wellbore after being discharged from the outer tube 16, are drawn through a port 20 into the inner tube 12 and pumped to the surface.
In the arrangement described above, tension may be pulled from the surface on the tubing string, which is anchored in the wellbore. Such tension is pulled to eliminate buckling and flexing of the tubing string. Such tension may also result in the premature wear and failure of the pumping components.
When tension is pulled on the tubing string, prior art separator devices, such as the one described, are prone to failure. In particular, the inner tube is prone to fracture because of its rigid attachment to the outer tube. Additionally, because the inner tube is welded or permanently joined to the outer tube, repair or replacement of components of the device may be difficult or impractical.